Arrangement for conveying controlled portions of a product material to a weighing system

ABSTRACT

An arrangement for conveying product material to a weighing system includes an infeed for product material to be weighed and at least one dosing mechanism for controlled conveyor of product material portions from the infeed to a weighing system. The dosing mechanism includes a motor-driven transport screw formed as a helically-shaped rod positioned in an open trough for conveying the product material from the infeed to the weighing system, and a control unit for controlling the motor in order to deliver a desired portion of product material to the weighing system. This arrangement provides a gentle, well-defined conveyance of product materials that are not suited for vibrational conveyance or conveyance by a screw conveyor in a tubular housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit, under 35 U.S.C. §119(e), ofprovisional U.S. Application No. 60/677,524, filed May 4, 2005, thedisclosure of which is incorporated herein by reference.

FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a weighing arrangement such as amultihead weigher comprising an infeed or storage hopper (both to benamed as infeed) for product material to be weighed, and at least onedosing mechanism for controlled conveying of product material portionsfrom said infeed to a weighing system.

2. Background Art

In weighing arrangements of this kind, it is known to use a dosing orbatching mechanism comprising vibratory pans positioned as a trough forconveying product material from the infeed to the weighing system and tocontrol the vibration in time and intensity in order to deliver adesired portion of product material to the weighing system. Suchweighing arrangement can be used for a broad range of product materials,as long as the product materials can be conveyed by vibration in asufficiently stable and organized manner. An alternative way ofproviding the delivery of desired portions of product material to aweighing system is to provide a screw conveyor in a tubular housing,which is suitable for controlled transport of particulate or pulverulentmaterials, such as e.g. known from EP 1 439 379. However, normal screwconveyors impose a relatively high mechanical influence on the productmaterial. Such mechanical influence should, however, be avoided inconnection with sensitive products. Thus, in connection with sensitive,sticky and/or flexible product materials, such as poultry, fish, freshmeat, marinated meat and corresponding lumpy and/or sticky materials,neither the vibrational nor the screw conveyor conveyance of the productmaterial will be sufficiently stable, well-defined, and gentle, andwill, thus, not be providing the required conveyance of these types ofproducts.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a weighingarrangement of the kind referred to above, with which it is possible toprovide a well-defined conveyance of product materials, which are notsuited for vibrational conveyance. This object is achieved with aweighing arrangement for weighing sticky and/or flexible productmaterial, such as fresh meat, marinated meat, poultry, fish andcorresponding lumpy and/or sticky materials, which according to thepresent invention comprises:

-   -   an infeed for product material to be weighed; and    -   at least one dosing mechanism for controlled conveying of        product material portions from the infeed to a weighing system;    -   wherein the dosing mechanism comprises a motor-driven transport        screw formed as a helically-shaped member positioned in an open        trough for conveying the product material from the infeed to the        weighing system, and a control unit for controlling the motor in        order to deliver a desired portion of product material to the        weighing system.

The above arrangement comprises motor-driven transport screws formed asa helically-shaped member and providing a well-defined conveyance ofproduct material from the infeed to the weighing system, even if theproduct material is sticky and/or flexible, or for other reasons is notsuited for vibrational conveyance.

The positioning of the screw in an open trough provides a gentleconveyance, without imposing any significant mechanical influence orpressure on the product material.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed part of the present description, the inventionwill be explained in more detail with reference to the exemplaryembodiment of a weighing system according to the invention shown in thedrawings, in which:

FIG. 1 shows a top view of the infeed for product material and eighteenmotor-driven transport screws positioned in troughs for conveying theproduct material from the infeed to a weighing system;

FIG. 2 shows a cross sectional view of the arrangement in FIG. 1, takenalong line along line A-A of FIG. 1;

FIG. 3 shows a detail, enclosed within the circle B in FIG. 2,indicating an example of a connection between the motor and thetransport screw; and

FIG. 4 is a cross-sectional view of an alternative embodiment of anoptional core used in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus shown in FIG. 1 comprises an infeed 1 having eighteendosing mechanisms 3 positioned symmetrically along the circumference ofinfeed 1. Eighteen is considered an exemplary number of dosingmechanisms, but the number in practice may be as few as two, and as manyas forty or more. Each dosing mechanism 3 comprises a trough 4, in whicha transport screw 5 in the form of a helically-shaped member ispositioned and driven by a motor 7 (see FIG. 3). As shown in FIG. 3, thetransport screw 5 is configured as a rod formed into a helix. The trough4 comprises a bottom part with a diameter that is greater than or equalto the outer diameter of the transport screw 5. Positioned coaxiallywith the transport screw 5 is a core 6, which is considered to beoptional, and which core 6 may have any diameter less than or equal tothe inner diameter of the transport screw 5.

The infeed 1, shown in cross section in FIG. 2, comprises a conicalcentral part 2, which provides a distribution of product materialtowards a peripheral outer wall 12 of the infeed 1. The conical centralpart 2 of the infeed ends at a distance from the outer wall 12 of theinfeed, and therebetween the product material falls down into theindividual troughs 4, in which the transport screw 5 and the optionalcore 6 are positioned to convey product material radially out of theinfeed 1 in a controlled manner in order to deliver controlled portionsof product material to a weighing system 15 positioned below theradially outer end of the troughs 4.

Preferably, the helically-shaped member of the transport screw 5 has anincreasing pitch along its length in order to improve the gentletransport of the product material.

As shown in FIG. 3, the connection between the motor 7 and the transportscrew 5 comprises a bushing 8 onto which the transport screw 5 isconnected permanently, e.g. by welding. Alternatively, the bushing 8 maybe integrated into the core 6, if the latter is present. The bushing 8comprises a pin 9 providing a non-rotational connection to amotor-driven axle 14 and a click-connection mechanism 10, e.g. providedby means of a spring (not shown) and a ball (not shown), the ball beingpressed into a recess provided in the motor axle 14. Theclick-connection mechanism 10 allows for ease of assembly anddisassembly for cleaning, maintenance, and replacement of the transportscrew 5 and/or the core 6.

The motor 7 is preferably positioned in an inner motor compartmentdefined within the confines of the outer wall 12 and under the conicalcentral part 2. The troughs 4 extend through corresponding openings inthe outer wall 12 of the infeed 1. In order to avoid leakage of productmaterial from the troughs 4 into the inner motor compartment, a sealingarrangement 11 is provided between the motor axle 14 and the outer wall12 of the trough 4.

The mounting of the motor 7, and the possible provision of supplementarybearings (not shown) for the axle 14 of the motor, are provided in aconventional way, and no detailed explanation is required at this pointfor those of ordinary skill in the art.

The components in contact with the product material are preferably madeof stainless steel, but other materials, such as plastic, for example,can be used for different reasons.

The above-described apparatus functions in the following way: Productmaterial to be weighed is conveyed to the infeed 1 in a controlledmanner in order to keep a mainly constant level of product material inthe infeed 1. The product material is distributed to the individualdosing mechanisms 3 by the conical central part 2 of the infeed.Suitable sloping surfaces between the individual troughs 4 of the dosingmechanisms 3 may be provided in order to lead the product material intothe individual troughs 4. Each dosing mechanism 3 delivers predeterminedportions of product material to the related weighing system 15 bysignals from a control unit 17 for the overall control for the weighingarrangement. The control unit 17 is operable to control the rotationalspeed and/or operational duration of the motor 7 so that a controlled,well-defined portion of product material is delivered by the controlledspeed of the motor 7 during a controlled period of time. In order tooptimize the dosing, the subsequent weighing of the delivered portion bythe weighing system provides a signal that is fed to the control unit17, which is then operated to adjust the period of time and/or the motorspeed in order to adjust the dosage of product material from eachindividual dosing mechanism 3.

Typical values for the rotational speed of the transport screw 5 are10-100 revolutions per minute, and typical periods of running times arebetween 50 and 2000 ms.

The following weighing and combination of dosed partial portions tofinal portions shall be as close as possible to the desired weight ofthe final portions by combining a predetermined number of dosed andweighed portions, is well-known within the art, and need not beexplained in further detail.

The invention has been described above and explained in connection witha specific embodiment thereof, as shown in the drawings; however, manyvariations are evident for those skilled in the art without departingfrom the following claims. Among such natural deviations are variationsin the number of dosing mechanisms 3, the provision of cores 6 having asmaller diameter, the provision of removable or replaceable cores and/ortransport screws having different diameters for conveying differentproducts and/or providing different speeds of conveyance, and thepossibility of providing the core 6 with another outer form other thanthe cylindrical form shown in FIG. 1, such as. for example, a core 6′(FIG. 4) with a fluted outer surface. Furthermore, the core may be keptstationary while rotating the transport screw 5 instead of being rotatedsynchronously with the transport screw 5. It will also be evident thatthe opening in the side 12 of the infeed 1, through which the trough 4extends, has to be adapted to the product material to be conveyed by thedosing mechanism 3.

1. An arrangement for conveying sticky and/or flexible product material to a weighing system, comprising: an infeed configured to hold the product material for conveyance to the weighing system; and a dosing mechanism operable for controllably conveying product material portions from the infeed to the weighing system, the dosing mechanism comprising: a trough connected to the infeed and configured to receive product material from the infeed; a motor-driven transport screw configured as a rod defining a helix and positioned in the trough, the transport screw being arranged and operable to convey the product material from the trough to the weighing system; a core having a fluted outer surface positioned inside the transport screw; and a control unit operable to control the driving of the transport screw so as to convey a desired portion of product material to the weighing system.
 2. The arrangement of claim 1, wherein the helix defined by the rod has an increasing pitch along its length.
 3. The arrangement of either of claims 1 or 2, wherein the core is rotated synchronously with the transport screw.
 4. The arrangement of either of claims 1 or 2, wherein the core is kept stationary while the screw is rotated.
 5. The arrangement of either of claims 1 or 2, wherein the core is a first core having a first diameter and is exchangeable with at least one second core having a second diameter different from the first diameter.
 6. The arrangement of either of claims 1 or 2, wherein the transport screw has an outer diameter, and wherein the trough comprises a bottom part having a cylindrical form with a diameter equal to or greater than the outer diameter of the transport screw.
 7. The arrangement of claim 6, wherein the trough extends through an opening in a side of the infeed.
 8. The arrangement of either of claims 1 or 2, wherein the infeed comprises a substantially conical central part, and wherein the arrangement comprises a plurality of dosing mechanisms positioned in a circular pattern around the central part the central part being configured to direct the product material radially outward to the plurality of dosing mechanisms.
 9. The arrangement of claim 8, wherein each of the dosing mechanisms comprises a transport screw and an associated motor operable to drive the transport screw, and wherein the motors are positioned under the central part.
 10. The arrangement of either of claims 1 or 2, wherein the dosing mechanism further comprises: a motor operably connected to the transport screw so as to drive the screw; and a clip-on mechanism detachably connecting the transport screw to the motor.
 11. The arrangement of either of claims 1 or 2, wherein the controller is operable to control the drive speed and running time of the transport screw.
 12. The arrangement of claim 11, wherein the controller is operable to receive information on the weight of the product material portions, and to adjust the drive speed and running time in response to the information.
 13. The arrangement of either of claims 1 or 2, wherein the arrangement comprises at least two dosing mechanisms. 